C# Get Generic Type Name

Question

I need some way to get the Name of a Type, when type.IsGenericType = true.

    Type t = typeof(List);
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Answer 1

I know this is an old question, but a colleague and myself needed to do this for some intellisense/roslyn work. The optimal solution appeared to be Ali's solution, but it doesn't work for nested types:

    int i = 1; //would work
    List listTest = new List(); //would work
    Dictionary dictTest = new Dictionary(); //would work
    Dictionary> nestTest = new Dictionary>(); //would fail
    Dictionary>>> superNestTest = new Dictionary>>>(); //would fail
    Dictionary>> superNestTest2 = new Dictionary>>(); //would fail

In order to solve these issues, I converted the function into a recursive method:

public static class TypeExtensions
{
    public static string GetFriendlyName(this Type type)
    {
        string friendlyName = type.FullName;
        if (type.IsGenericType)
        {
            friendlyName = GetTypeString(type);
        }
        return friendlyName;
    }

    private static string GetTypeString(Type type)
    {
        var t = type.AssemblyQualifiedName;

        var output = new StringBuilder();
        List typeStrings = new List();  

        int iAssyBackTick = t.IndexOf('`') + 1;
        output.Append(t.Substring(0, iAssyBackTick - 1).Replace("[", string.Empty));
        var genericTypes = type.GetGenericArguments();

        foreach (var genType in genericTypes)
        {
            typeStrings.Add(genType.IsGenericType ? GetTypeString(genType) : genType.ToString());
        }

        output.Append($"<{string.Join(",", typeStrings)}>");
        return output.ToString();
    }
}

running for the previous examples/test cases yielded the following outputs:

System.Int32
System.Collections.Generic.List
System.Collections.Generic.Dictionary
System.Collections.Generic.Dictionary>
System.Collections.Generic.Dictionary>>>
System.Collections.Generic.Dictionary>>

I spent some time trying to resolve the nested types issue so wanted to document this here to ensure anyone else in future can save some considerable time (and headaches!). I have checked the performance as well, and it is in the microseconds to complete (8 microseconds in the case of the last scenario:

Performance results
(Variables names used from original scenario list)
"i" | 43uS
"listTest" | 3uS
"dictTest" | 2uS
"nestTest" | 5uS
"superNestTest" | 9uS
"superNestTest2" | 9uS
Average times after performing the above code 200 times on each scenario